1. Field of Invention
The invention relates to a device for winding and locking a drawstring. The invention finds a particular application within the context of lacing personal articles, such as garments, footwear, helmets, protective gears, by enabling lacing and, more generally, fast and accurate tightening.
2. Background Information
A number of devices for winding and locking drawstrings are known. Generally, such devices comprise a fixed support connected to the article, a spool for winding or unwinding the lace at its periphery, as well as mechanisms for locking the spool in a winding position. An element, typically a knob, is provided to enable the user of the article to control the locking of the spool in position.
For example, the document U.S. Pat. No. 8,468,657 discloses a lace winding and locking device comprising a spool and mechanisms for blocking its rotation. In this document, the blocking mechanisms are comprised of three thin engagement rods affixed to the spool at one of their ends, and the other end comprises a locking surface adapted to be embedded into teeth to block the rotation of the spool. Each engagement rod forms a pawl. This document also shows an unlocking surface carried by each of the engagement rods and adapted to come into contact with a stud driving the knob to cause the engagement rods to flex.
The presence of the three engagement rods makes it possible to balance the spool and to distribute rotational retention forces in three points. However, this has the disadvantage of rendering the construction of this system complex and hyperstatic.
In addition, this system has, in practice, proven to be relatively fragile and not suitable to withstand high tension force from the lace.
The fragility is further accentuated by the fact that the locking and unlocking surfaces are positioned in the vicinity of one another.
The patent IT-A-1 220 811 also discloses a device for winding and locking a lace, which partially solves the problem of fragility. This document provides a single massive pawl which comes into contact with peripheral teeth.
The mechanisms for disengaging the pawl from the teeth are formed by a cam surface provided on the pawl and positioned in the vicinity of the axis. Also provided is a spring pushing the pawl into position.
Such positioning is unfavorable in terms of moment, and the user must exert a relatively substantial torque to proceed with the loosening, making such loosening difficult. Furthermore, the presence of a spring in this device makes the construction of the device more complex and heavier. However, for certain applications, especially for garments or footwear, or similar articles, lightness is a very important parameter.
A problem underlying the invention is to design a device for winding and locking a drawstring, which is simple in design while having improved strength.